Armature for a miniature DC motor

ABSTRACT

An armature ( 11 ) for a miniature DC motor constitutes a rotor provided in an interior of a casing and armature windings ( 10 ) are wound around an iron core ( 9 ) in the form of a coil. In this armature ( 11 ), insulators ( 25, 26 ) made of paper including at least ordinary paper and having an electric insulation property adhere to at least portions, of both end faces of the iron core ( 9 ), on which the armature windings are wound. Thus, the iron core and the armature windings do not come into direct contact with each other.

TECHNICAL FIELD

The present invention relates to an armature for a miniature directcurrent motor (hereinafter simply referred to as a miniature motor).More particularly, it relates to an armature for a miniature DC motorwhich may enhance the motor characteristics by keeping an insulationperformance between an iron core and armature windings at low cost.

BACKGROUND ART

A miniature motor has been extensively used in a wide field including avariety of equipments. There is a demand of the improvement in a heatresistance, machining workability, assembling workability or the like inaddition to the reduction at cost and the enhancement of the motorcharacteristics.

In an armature to constitute a rotor which is provided in an interior ofthe miniature motor, armature windings (hereinafter referred to aswindings) are wound around an iron core in the form of a coil. In orderto insulating the iron core and the windings from each other, there area variety of approaches.

For instance, there is one case in which epoxy resin coating, or thelike, is applied to the iron core or there is another case in which theiron core is covered with a sheet or a molding material made of resinformed in conformity with a shape of the iron core (see Japanese UtilityModel Application Laid-Open No. Hei 2-60475, Japanese Patent ExaminedPublication No. Sho 31-7964 and Japanese Utility Model ApplicationLaid-Open No. Hei 5-70150).

By the way, in the armature, since the windings are wound on the ironcore, it is likely that an insulation failure would occur at edgeportions of both end faces of the iron core. In the case in which theabove-described coating is applied in order to avoid this insulationfailure, it is difficult that the coating material adheres to the edgeportions which most need the insulation performance.

When the coating becomes thick for this reason, internal spaces of theiron core for winding the wire become small. As a result, there is afear that a winding number of the possible windings becomes small andthere is a fear that the characteristics of the motor would be degraded.

Also, when the coating material is sprayed, the coating is applied toportions which do not need the coating. In order to perform the coatingwhich is thin with a high reliability in order not to reduce the windingnumber of the windings, a high technology equipment and a hightechnology are necessary.

On the other hand, in the case in which the iron core is covered withthe above-described sheet or molding which is made of resin, apredetermined thickness is needed to some extent in view of the moldingtechnology. As a result, the internal spaces become small so that thewinding number is decreased and it is difficult to thin the miniaturemotor.

A heat resistance temperature of the resin which is the material for thesheet or the like is low in a range of about 120° to 180° C. Also thereis a fear that the sheet is offset. In addition, when the sheet or thelike is produced, scrap materials are by-products, accordingly there isa fear that an environmental problem is lead.

Japanese Utility Model Examined Publication No. Sho 31-12529 andJapanese Patent No. 2807534, and the like, disclose an arrangement inwhich insulators made of paper are provided on the iron core. However,these technologies are not directed to a heat resistance, a machiningworkability and an assembling workability. Also, these technologies arenot directed to an arrangement for preventing an insulation failure atthe edge portions by providing insulators at both end faces of the ironcore.

In order to overcome the above-noted difficulties, an object of thepresent invention is to provide an armature for a miniature DC motorwhich may enhance the characteristics of the motor by keeping aninsulation performance between an iron core and armature windings at lowcost. Also, another object of the present invention is to elevate a heatresistance temperature of the armature.

DISCLOSURE OF THE INVENTION

An armature for a miniature DC motor, according to the presentinvention, constitutes a rotor provided in an interior of a casing ofthe miniature DC motor, windings of the armature being wound around aniron core in the form of a coil, wherein insulators, which are made ofpaper including at least ordinary paper and have an electric insulationproperty, adhere to at least portions, of both end faces of the ironcore, on which the armature windings are wound so that the iron core andthe armature windings do not come into direct contact with each other.

It is preferable that the insulators are either an impregnated paper inwhich a substance having a waterproof effect is impregnated with anordinary paper or a laminated paper in which an ordinary paper and athin plate made of resin are laminated to each other.

Incidentally, an armature for a miniature DC motor constitutes a rotorprovided in an interior of a casing of the miniature DC motor, windingsof the armature being wound around an iron core in the form of a coil,wherein insulators made of paper composed of a vulcanized fiber mayadhere to at least portions, of both end faces of the iron core, onwhich the armature windings are wound so that the iron core and thearmature windings do not come into direct contact with each other.

Also, an armature for a miniature DC motor constitutes a rotor providedin an interior of a casing of the miniature DC motor, windings of thearmature being wound around an iron core in the form of a coil, whereininsulators made of soft resin film may adhere to at least portions, ofboth end faces of the iron core, on which the armature windings arewound so that the iron core and the armature windings do not come intodirect contact with each other.

In this case, it is preferable that a material of the soft resin film isselected from a group consisting of polyester synthetic resin,low-density polyethylene, high-density polyethylene, polyamide,polypropylene, polyvinyl chloride and polyvinylidene chloride.

In the armature, it is preferable that, under a condition that theinsulators are bent from edge portions of both the end faces of the ironcore toward internal spaces, the armature windings are wound around theiron core through the insulators.

Incidentally, in the armature, the insulators may be made of thick paperand have substantially the same shape as that of the end faces at theportions of both the end faces of the iron core or have such a shape inorder that the insulators somewhat project from the edge portions ofrespective end faces of arm portions and anchor portions of the ironcore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 5 show an example of an embodiment of the present invention.

FIG. 1 is a frontal view in cross section of one side of a miniature DCmotor.

FIG. 2 is an exploded perspective view showing a structure of anarmature according to the present invention.

FIG. 3 is a perspective view showing the armature in which insulatorsare provided to an iron core.

FIGS. 4A-B is illustrations showing the insulators attached on a releasecoated paper.

FIGS. 5A-C is cross-sectional views taken along a line V—V of FIG. 3.

BEST MODE FOR EMBODYING THE INVENTION

An example of an embodiment of the present invention will now bedescribed with reference to FIGS. 1 to 5.

FIG. 1 is a frontal view in cross section of one side of a miniature DCmotor having an armature according to the present invention. FIG. 2 isan exploded perspective view of the armature. FIG. 3 is a perspectiveview showing the armature in which insulators are provided to an ironcore. FIG. 4 is illustrations showing the insulators attached on arelease coated paper. FIG. 5 is cross-sectional views taken along a lineV—V of FIG. 3.

As show n in FIG. 1, the miniature motor (miniature DC motor) 1 isprovided with a casing 4 in which a stator 3 is mounted on an innersurface 2 of the casing 4, and a rotor 5 mounted in an interior of thecasing 4. A rotary shaft 6 of the rotor 5 is rotatably support ed tobearing portions 7 and 8 provided to the casing 4.

The rotor 5 is provided with the rotary shaft 6, an armature 11 and acommutator 12. The rotary shaft 6 extends in a direction of a centerlineCL which is to be a rotary center. In the armature 11, windings(armature windings) 10 are wound around an iron core 9 mounted on therotary shaft 6 in the form of a coil. The commutator 12 is mounted onthe rotary shaft 6 and is electrically connected to the windings 10.Brushes 13 mounted on the casing 4 are slidingly engaged with thecommutator 12.

As shown in FIGS. 2 and 3, the iron core 9 of the armature 11 is calleda multilayer core, and the iron core 9 is formed by laminating aplurality of thin plate type core elements 14. The iron core 9 isprovided with a plurality (for example, three) of salient poles 20.

Each salient pole 20 is provided with an arm portion 21 extendingradially outwardly and an anchor portion 22 extending in acircumferential direction on both sides from a tip end portion of thearm portion 21. The windings 10 are mainly wound around the arm portions21. The rotary shaft 6 is fixedly inserted in a central portion of theiron core 9.

Insulators 25 and 26 having an electric insulation property adhere withadhesives to at least portions, of both end faces 23 and 24 of the ironcore 9, on which the windings 10 are wound. That is the reason why theiron core 9 and the armature windings 10 do not come into direct contactwith each other.

Paper material including at least ordinary paper or paper materialcomposed of vulcanized fiber is used for the insulators 25 and 26. Theinsulators 25 and 26 are for example formed into thin plates, made ofordinary paper, having shapes corresponding to the shapes of the endfaces 23 and 24.

One insulator 25 is mounted on one end face 23 and the other insulator26 is mounted on the other end face 24, respectively. Holes 27 forallowing the rotary shaft 6 to pass therethrough are formed in thecentral portions of the insulators 25 and 26.

The windings 10 are wound in the form of a coil around the arm portions21 and the anchor portions 22 of the three salient poles 20 under thecondition that the insulators 25 and 26 are brought into intimatecontact with both the end faces 23 and 24 of the iron core 9 to therebyassemble the armature 11.

Almost all of the windings 10 are wound around the arm portions 21 andsimultaneously the windings 10 are also wound around the anchor portions22. Almost all of the windings 10 are received in internal spaces 28defined between the adjacent salient poles 20 and 20 of the iron core 9.

In the insulators 25 and 26 shown in FIGS. 2 and 3, the holes 27 forallowing the rotary shaft 6 to be inserted therethrough are round inshape. Incidentally, it is preferable that a recess is formed in theposition of the hole 27 of the insulators 25 and 26 so that a projection(not shown) of the commutator 12 may engage with the recess.

With such an arrangement, the commutator 12 is brought into intimatecontact with the insulator and at the same time, the projection of thecommutator 12 is engaged with the recess of the insulator so that thecommutator 12 is fixedly positioned to the armature 11.

The reason why the recess is formed in the insulator is as follows.Namely, in the case in which the recess is also formed in a position ofa hole through which the rotary shaft is inserted in the iron core,magnetic lines of force which are generated from a magnetic field formedby permanent magnets and which pass through the iron core are decreasedto thereby reduce a torque of the motor. Accordingly, it is preferablethat the recess is formed only in the insulator but not in the ironcore.

The material for the insulators 25 and 26 may be selected from ordinarypaper such as fine quality paper or reproduced paper, paper (impregnatedpaper) in which a substance having a waterproof effect is impregnatedwith an ordinary paper, a paper (laminated paper) in which the ordinarypaper and a thin plate made of resin are laminated on each other, thepaper made of vulcanized fiber, and the like.

Normally, in the case in which the paper adheres to the iron core, therewould be no problem under high moisture circumstances to some extent.However, in the case in which the moisture-proof is the importantfactor, it is preferable to use the impregnated paper in which thesubstance having the waterproof effect is impregnated with the ordinarypaper. The above-described substance having the waterproof effect may beat least one selected from a group of resin, wax and oil.

Since the impregnated paper and the laminated paper are made of resin orthe like as basic material, it is possible to prevent an expansion dueto a water absorption. This prevention of the expansion due to the waterabsorption means to prevent the insulators from expanding to cause anadverse affect such as the contact with other parts. Also, theimpregnated paper and the laminated paper are superior in bendabilityand elongation property.

For instance, when an acrylic resin is used as basic material for suchthe impregnated paper and the laminated paper, the acrylic resin issuperior particularly in bendability and elongation property. As aresult, it is possible to easily mount, on the iron core 9, theinsulators 25 and 26 which are formed into a predetermined shape.Accordingly, it is easy to perform an assembling work of the armature11.

The vulcanized fiber is the paper manufactured through a predeterminedprocess. This predetermined process is as follows. The fiber originalpaper manufactured from material such as a selected chemical pulp or acotton fiber is processed with zinc chloride solution and is partiallycured and then is rolled up, and thereafter it is subjected to waterwashing, drying, pressing, polishing and the like.

There are many kinds of vulcanized fiber. It is normal that thevulcanized fiber has a moisture content of 6 to 10% and has the waterabsorption and hygroscopicity. It is preferable for material of thevulcanized fiber that the material has low water absorption andhygroscopicity in order to suppress or prevent the deformation of theshape thereof, because the extent of the shrinkage and expansion of thematerial due to the drying and moisture absorption is suppressed.

Since the vulcanized fiber is superior in electric insulation property,it is possible to positively ensure the insulation between the iron core9 and the windings 10 at low cost. Also, a formation of the vulcanizedfiber is dense and strong. Accordingly, there is no fear that thevulcanized fiber would be broken when it is to be applied to the ironcore 9. The assembling work of the armature 11 is facilitated.

Also, in some cases, a thickness of the insulators 25 and 26 is thin orsomewhat thick. In view of the workability when the paper is mounted onthe iron core 9, it is preferable that the paper for the insulators 25and 26 is a long fibrous paper having the elongation property. A fiberlength of the long fibrous paper is, for example, in a range of 90 to135 μm.

It is possible to use a soft resin film for the insulators 25 and 26instead of the one made of paper. The material for this soft resin filmmay be selected from, for example, polyester synthetic resin such aspolyethylene terephthalate, low-density polyethylene (LDPE),high-density polyethylene (HDPE), polyamide, polypropylene, polyvinylchloride, polyvinylidene chloride, and the like.

The adhesive is applied to either one or both of the insulators and theiron core 9, accordingly the insulators 25 and 26 adhere to the ironcore 9 with the adhesive. It is preferable that this adhesive is thematerial which has a heat resistance and the waterproof property. Forinstance, when an acrylic adhesive is used, since it has the heatresistance and a good adhesiveness, the bonded insulators may beprevented from being peeled and an offset of the insulators may beprevented. As a result, it is easy to perform the assembling work of thearmature 11.

For example, as shown in FIG. 4(A), the ordinary paper, the impregnatedpaper, the laminated paper, the vulcanized fiber or the soft resin filmfor using as the insulators 25 and 26 is formed into a predeterminedshape and simultaneously the adhesive is applied to one surface of theinsulators. A plurality of pieces of the insulators are attached on arelease coated paper 30 in the form of a sheet. Under this condition,when the release coated paper 30 is provided to a process for assemblingthe armature 11, it is possible to enhance the efficiency of themounting work of the insulators 25 and 26.

Some of the above-described material and thickness are used suitably incombination for the insulators 25 and 26, and the insulators are mountedon the iron core 9. The insulators may be provided to portions, of boththe end faces 23 and 24 of the iron core 9, on which the windings 10 areto be wound. Namely, it is not always necessary to cover entire portionsbetween both end faces of the anchor portions 22 of the salient poles 20with the insulators.

Accordingly, for instance, as shown in FIG. 4(B), it is possible to useinsulators 25 a and 26 a in which outer portions 31 corresponding to theanchor portions 22 are formed into a relatively small size. The adhesiveis applied to the plurality of insulators 25 a and 26 a and theinsulators 25 a and 26 a are attached on the release coated paper 30.

As shown in FIGS. 5(A) and (B), the insulators 25 and 26 are bent fromedge portions 32 of both the end faces 23 and 24 of the iron core 9toward the internal spaces 28 (FIG. 3). Under this condition, thewindings 10 are wound around the iron core 9 through the insulators 25and 26.

In FIG. 5(A), since the insulators 25 and 26 are thin, there is shown astate in which the insulators 25 and 26 are bent along the iron core 9at the edge portions 32. In FIG. 5(B), the impregnated paper, thelaminated paper or the vulcanized fiber which has a somewhat largethickness is used as the insulators 25 and 26. Then, the impregnatedpaper or the like is heated at the edge portions 32 by a soldering toolor the like to obtain a shape of the insulators bent somewhat toward theinternal spaces 28.

Since a plurality of core elements 14 which constitute the iron core 9are formed by punching-out with a press machine, there is a case inwhich the cut face by the punching-out would be rough. For this reason,when the windings 10 are brought into direct contact with the iron core9 at each edge portions 32 between the anchor portions 22 and the armportions 21 of the iron core 9, there is a fear that the windings 10 areabraded by the edge portions 32 so that an insulation coating of thewindings 10 would be removed. As a result, there is an insulationfailure and an electric leak.

Therefore, according to this embodiment, both the end faces 23 and 24 ofthe iron core 9 and the edge portions 32 thereof are covered with theinsulators 25 and 26. Accordingly, there is almost no fear that thewindings 10 and the iron core 9 would come into direct contact with eachother, and the insulation performance between the iron core 9 and thewindings 10 may be ensured.

In the case in which the insulators are made of soft resin film, sincethe insulators are softer than the paper, the insulators may readily bebent from the edge portions 32 of the iron core 9 toward the internalspaces 28 and may be extended longitudinally along the side surfaces 35on both sides and may adhere thereto. Thus, the insulators cover almostall of the side surfaces 35 to further ensure the insulation performancein good condition.

Incidentally, in a case in which the insulators 25 and 26 are thin, itis preferable that a plurality of insulators are overlapped and used inplace. Even if these insulators would be broken on the side of the ironcore 9, there is no fear that the insulation failure would occur.

Also, in an example shown in FIG. 5(C), the insulators 25 b and 26 b aremade of thick paper. The insulators 25 b and 26 b have substantially thesame shape as that of the end faces 23 and 24 at the portion, of boththe end faces 23 and 24 of the iron core 9, on which the windings 10 arewound. Alternatively, the insulators 25 b and 26 b have such a shape inorder that they may project somewhat (for example, by a predetermineddimension b) from the edge portions 32 of respective end faces of theanchor portions 22 and the arm portions 21 of the iron core 9.

With such an arrangement, it is possible to ensure the same workingeffect as that described according to FIGS. 5(A) and (B). In addition tothis, in comparison with the case shown in FIG. 5(B), since a processfor bending the insulators is dispensed with, the assembling work may besimplified.

As described above, according to the present invention, the insulators25, 25 a, 25 b, 26, 26 a and 26 b adhere to at least portions, of boththe end faces 23 and 24 of the iron core 9, on which the windings 10 arewound so that the iron core 9 and the windings 10 do not come intodirect contact with each other. The insulators are formed out of thepaper or the soft resin film having the electric insulation property.

Thus, it is possible to keep the insulation performance between the ironcore 9 and the windings 10 at low cost to thereby enhance thecharacteristics of the miniature motor 1.

In the above-described embodiment, the edge portions 32 of the ironcore, on which the possibility that the electric leak due to theinsulation failure occurs is highest, are covered by the insulators 25,25 a, 25 b, 26, 26 a and 26 b so that the windings 10 are prevented fromcoming into direct contact with the edge portions 32 of the iron core.

Thus, it is possible to prevent the insulation coating of the windings10 from being removed at the iron core edge portions 32. As a result,there is no fear that the insulation failure would be caused.Accordingly, it is possible to prevent the electric leak by keeping theinsulation performance between the iron core 9 and the windings 10 tothereby enhance the characteristics of the miniature motor 1.

When the insulators made of paper including at least ordinary paper areused, since a carbonizing temperature of the ordinary paper is about700° C., it is possible to keep high a heat resistance temperature ofthe armature 11 for the miniature motor 1 at low cost. In particular, inthe case in which the ordinary paper is independently used as theinsulators, the heat resistance is enhanced.

On the other hand, as shown in FIG. 5(B), in the case in which theinsulators 25 and 26 are bent, since it is difficult to perform thesebending works with only the ordinary paper, it is possible to performthe bending work and the drawing work when the impregnated paper or thelaminated paper is used. Thus, it is possible to readily mount on theiron core 9 the insulators 25 and 26 formed in a predetermined shape tothereby improve an assembling workability of the armature 11.

It is preferable that the insulators are thin as much as possiblebecause a rate (winding occupying rate) for the windings 10 to occupythe internal spaces 28 of the iron core 9 is increased and in order toincrease the winding number for the possible winding. However, when theinsulators are thin, they are softened so that a rigidity of theinsulators would be weak. Then, in the winding work of the windings 10,there is a fear that wrapping of the insulators or peeling thereof wouldoccur.

Therefore, in the embodiment, the insulators 25, 25 a, 25 b, 26, 26 aand 26 b adhere to the iron core 9 with adhesives. Thus, it is possibleto prevent these troubles and to aim the enhancement of the efficiencyof the winding work. When once the windings 10 are wound, since theinsulators are depressed by the windings 10, there is no serious problemin the heat resistance in adhesives thereafter.

Also, since the insulators may be thinned, the internal spaces 28 becomelarge. It is therefore possible to increase the winding number for thepossible windings and to enhance the characteristics of the motor toreadily thin the motor.

When the paper including the ordinary paper having the heat resistanceis used as the insulators, it is possible to enhance the heat resistancetemperature of the armature at low cost. In the case in which theimpregnated paper or the laminated paper is used as the insulators, itis possible to enhance a moldability (i.e., workability) of theinsulators and the assembling workability of the armature in addition tothe enhancement of the heat resistance.

In the case in which the vulcanized fiber is used as the insulators, itis possible to positively ensure the insulation performance in additionto the enhancement of the heat resistance temperature. Also, in thiscase, it is possible to enhance the assembling workability of thearmature since the insulators would hardly be broken.

Also, when the insulators are made of paper, there is almost no problemin environmental aspects, and there is no disadvantage in the case inwhich the coating material is used.

In the case in which the soft resin film is used as the insulators, thefilm is softer than the paper and is weak in restoring force.Accordingly, the insulators may readily be bent at the edge portions ofthe iron core and may be mounted thereon. It is possible to readilyperform the assembling work even for the armature for a miniature sizemotor.

With the above-described arrangement according to the present invention,it is possible to enhance the characteristics of the motor by ensuringthe insulation performance between the iron core and the armaturewindings of the miniature DC motor at low cost.

Also, when the insulators made of paper insulate between the iron coreand the armature windings, it is possible to elevate the heat resistancetemperature of the armature in addition to the above-described effect.

Incidentally, the same reference numerals in each drawing represent thesame or corresponding portions.

INDUSTRIAL APPLICABILITY

As described above in detail, the armature for the miniature DC motoraccording to the present invention is suitably applied to the armatureinstalled in the miniature motor which is used in an optical precisionequipment such as a miniature camera, an audio visual equipment such asa CD (Compact disk) player, an OA (Office automation) equipment such asa copying machine, a home electric appliance such as a hair drier, anautomotive electric equipment, a toy and the like.

What is claimed is:
 1. An armature for a miniature DC motor forconstituting a rotor provided in an interior of a casing of saidminiature DC motor, said armature comprising: an iron core; and armaturewindings wound around said iron core in the form of a coil, wherein saidarmature windings are wound on insulators made of paper, said insulatorshaving an electric insulation property, and adhered to at least portionsof both end faces of said iron core so that said iron core and saidarmature windings do not come into direct contact with each other. 2.The armature for a miniature DC motor according to claim 1, wherein saidpaper is independently used as said insulators to thereby enhance a heatresistance.
 3. The armature for a miniature DC motor according to claim1, wherein said insulators comprise one of an impregnated paper in whicha substance having a waterproof effect, said substance being at leastone selected form a group of resin, wax and oil, is impregnated in apaper or a laminated paper having a fiber paper and a resin plate arelaminated to each other.
 4. The armature for a miniature DC motoraccording to claim 3, wherein an acrylic resin is used as a basicmaterial for said impregnated paper and said laminated paper.
 5. Thearmature for a miniature DC motor according to any one of claims 1, 2, 3or 4, wherein said paper is a long fibrous paper having an elongationproperty with a fiber length in a range of 90 to 135 μm.
 6. The armaturefor a miniature DC motor for constituting a rotor provided in aninterior of a casing of said miniature DC motor, said armaturecomprising: an iron core; and armature windings wound around said ironcore (9) in the form of a coil, wherein armature windings are wound oninsulators made of paper composed of a vulcanized fiber adhered to atleast portions of both end faces of said iron core so that said ironcore and said armature windings do not come into direct contact witheach other.
 7. An armature for a miniature DC motor for constituting arotor provided in an interior of a casing of said miniature DC motor,said armature comprising: an iron core; and armature windings woundaround said iron core in the form of a coil, wherein said armaturewindings are wound on insulators made of soft resin film adhered to atleast portions of both end faces of said iron core so that said ironcore and said armature windings do not come into direct contact witheach other, wherein under a condition that said insulators are bent fromedge portions of both the end faces of said iron core toward internalspaces, said armature windings are wound around said iron core throughsaid insulators.
 8. The armature for a miniature DC motor according toclaim 7, wherein a material of the soft resin film is selected from agroup consisting of polyester synthetic resin, low-density polyethylene,high-density polyethylene, polyamide, polypropylene, polyvinyl chlorideand polyvinylidene chloride.
 9. The armature for a miniature DC motoraccording to claim 1 or 6, wherein under a condition that saidinsulators are bent from edge portions of both the end faces of saidiron core toward internal spaces, said armature windings are woundaround said iron core through said insulators.
 10. The armature for aminiature DC motor according to claim 1 or 6, wherein said insulatorshave substantially the same shape as that of the end faces at theportions of both the end faces of said iron core or have such a shape inorder that said insulators project from the edge portions of respectiveend faces of arm portions and anchor portions of said iron core.
 11. Thearmature for a miniature DC motor according to claim 1, 6 or 7, whereinan acrylic adhesive is applied to either one or both of said insulatorsand said iron core so that said insulators adhere to said iron core withsaid acrylic adhesive.
 12. The armature for a miniature DC motoraccording to claim 1, 6 or 7, wherein a plurality of said insulators areoverlapped and used in place so that an insulation failure is preventedeven if said insulators would be broken on a side of said iron core.